lift pump going bad?

[rapidoxidationman]

The wonderful rapid-fire clicking sound one hears when first turning the key - as the glows are doing their thing - is easy to ignore... until it doesn't go with the smooth rhythm that one is used to hearing. Usually it sounds like it should, but sometimes it stutters, like someone is turning the power on and off to it at random. Sound like the dying gasps of a lift pump or what? The truck will have 140,000 on it by the end of the week.
Regards,
Rapid

[tom.mcinerney]

A good question, hope you get more responses. Most solenoid pumps beat fast until output comes up to pressure, then slow/quiet as the output checkvalve maintains pressure. I don't know about these.

[Turbine Doc]

Lift pump check from 98 manual paraphrased open pump outlet at hose fitting place 1 liter/1qt container under it, turn key on if more than 1/2 pt/.24 liter in 15 sec. check fuel pressure, if less than 1/2 pt in 15 sec check fuel suction if no problems found in either replace pump.

Fuel pressure min is 4 psi/27kPa easy place to measure is fuel filter bowl drain line install gauge with press gage attached, and drain cock opened; it is also a good place to capture collection to measure Gpm/Lpm instead of breaking pump outlet.

[rjschoolcraft]

Just curious...

My lift pump doesn't run until the key is turned to start position. I thought that's the way they all were. I've heard mine continue to run briefly after engine shut down, but never during the glow plug cycle. :confused:

[jjgmc96]

Just replaced mine at 100,000. It runs on glow cycle and a short time after I shut down, about long enough for the oil presure to bleed down? Old one didn't make any noise and read open with a meter.

[Turbine Doc]

Ronnie mine works the same, if I read the book description properly, the PCM controls it at 1st key on to more or less prime the system after that the PCM hands off to the OPS to control the relay during actual run I think it's the OPS bleed off that keeps it running at shutdown.

[rapidoxidationman]

I'm now wondering if it is my lift pump I'm hearing. The whirring is there during the glow and afterglow cycles and when the truck is cold (winter) it'll also keep going sometimes after the truck is shut down after a short trip in the morning. What am I listening to? It sounds like it is under the driver's seat outside the truck; I may take a minute to locate it tomorrow am if the snow's not too deep...
Rapid

[James Schaack]

rapid,

that should be your liftpump you are hearing. mine ('93) is located under the cab, drivers side, on the inside of the frame rail and i would imagine yours is the same. you'll see it if you look under. when considering liftpump problems, it is a good idea to feel the pump as well as listen for it. when my truck is running there is no way i can hear it run, but you i can feel the pump pulsating. this way you can check to see if the pump is running after the truck has started.

i just got done fixing my liftpump system yesterday, hadn't worked since i bought the truck in september. my problem turned out to be the oil pressure sensor. the sensor controls the oil pressure gauge and the operation of the liftpump while the truck is running. check out my recent thread entitled "liftpump relay??"

good luck and keep us updated!!

james

[ucdavis]

Rapidox- If your lift pump "ticking" took a different rhythm lately, you may have an OPS going bad. They develope burn spots on the contacts which prevent adequate contact to operate lift pump; but they take some time to die completely. New OPS is about $24-30. New IP is about $1000+ so its best to change out a suspect OPS if you think it isn't running properly (no lift gives inadequate fuel to IP so you run short of fuel on heavy accel. & keep IP from getting adequate lubrication).
Ronnie- Sounds like yours is A-OK.